Study And Optimization Of Structure Parameters Of The CO₂ Air Cooler

The rapid development of national economy,people are pursuing a higher life quality,which demands a higher level for food cold chain technology.The storage technology is a vital part of the cold chain logistics,and the air cooler is one of the core devices that used in cold storage refrigeration system.The optimize of its performance is of great significance to the cold storage energy consumption.Since the use of the traditional refrigerants is subject to environmental problems such as the ozone holes and the greenhouse effect,researchers begun to re-focus on natural refrigerants such as CO₂.Therefore,as a combination of both sides,the structure parameters optimization and the improvement of the performance of CO₂ air cooler are of great significance for the whole industry.In this paper,the influence of the structure parameters of the finned tube on the heat transfer performance of the CO₂ air cooler is calculated by an established mathematical model,and some suggestions are put forward based on the calculations.Secondly,Fluent has been used to simulate the influence of the structure parameters of the shroud on the performance of the axial fan in the air cooler,and two different outlet shapes are compared.Finally,the simulation results are verified by experiments,and some ideas are provided for optimizing the shape of the shroud.The main conclusions are as follows:（1）The numerical calculation shows that the structure parameters of the finned tube have important influence on the heat transfer performance of the CO₂ air cooler.The influences of tube row number,tube spacing and fin spacing are much greater than that of tube diameter and fin thickness.Considering that the above structure parameters also affect the size and cost of the air cooler,a compromise needs to be taken when making improvements.（2）The simulation results show that the inlet and outlet shape of the shroud has certain influence on the aerodynamic performance of the axial fan in the air cooler.The inlet of the shroud is changed from the right-angle interface to the arc interface,which can increase the air volume of the axial fan by 20%.The addition of an arc-shaped transition section or a gradually expanding transition section at the outlet also led a significant increase to the air volume,and the air volume increases about 7%.（3）The simulation results also show that with an arc-shaped inlet shroud or an arc-shaped transition section added to the outlet,the increase of the arc radius in a certain range can improve the air volume continuously.When the outlet is a gradually expanding transition section,there is the best expansion angle where has the max air volume.From the results,the arc-shaped transition section is superior to the gradually expanding transition section.（4）The experiments verify the influence of the shape and size of the inlet and outlet of the shroud.Compared with the simulation results,although there’s a gap between them,their trend is basically the same.To a certain extent,the reliability of the simulation results is verified.（5）The experimental results also show that the changes of the shape and size of the shroud have an improvement on the uniformity of the wind speed on the windward side.